Plant

Blackberries change colour from red to black as they ripen. Image by Thomas’ pics (CC BY 2.0 via Flickr)

In England at this time of year, the hedgerows along country lanes are full of delicious fruits called blackberries. Just last week I spent an enjoyable afternoon with friends gorging on blackberries along the route of an old railway line in Norwich (now a footpath and cycleway). The berries are a good source of vitamin C and antioxidants, and are commonly used in desserts and preserves. Although I love collecting and eating blackberries, I have a bit of a love-hate relationship with the plant that produces them, the bramble (Rubus fruticosus agg.).

Rubus fruticosus agg. isn’t a single species, but instead is a group (or aggregate; agg) of around 200-300 very similar species of shrub in the rose family that are very hard to tell apart (1). Like roses, brambles are covered in sharp thorns that help to protect the plant from herbivores (and humans). The thorns also help to make brambles a safe haven for many small birds and other wildlife.

Brambles grow wild across most of Europe and in the UK they can thrive in most environments (1). The white or pinkish flowers are self-fertile and can still produce seeds even in the absence of fertilization (a process called apomixis) to produce an army of clone plants (2). Furthermore, brambles can produce suckers – new shoots from buds in the roots – which helps them rapidly cover an area of ground. As a result, brambles are often among the first plants to colonise abandoned plots of land. This is great for wildlife and the casual blackberry picker, but it’s not so helpful if you are trying to work on said piece of abandoned land…

When some friends and I took on an allotment this year, our plot had been neglected for a while and contained quite a lot of brambles. We removed a lot of the plants but have left some to be our own personal blackberry patch. Removing brambles is not a fun business as the thorns can cut through clothes (and gardening gloves). For several weeks in the spring my arms and legs were covered in scratches and I often found bramble thorns impaled in my fingers. If you don’t manage to completely remove the whole root, the bramble is quite capable of growing a fresh shoot so we’ve had a few cheeky brambles reappearing in the vegetable beds.

Despite my moaning about brambles I must say that the blackberry crop from the allotment has been great. It is kind of ironic that our most successful crop this year is something we weren’t deliberately growing. All in all, if I had to summarize my relationship with the bramble at the moment, I would say: “it’s complicated”.

While giving my undergraduate class a tour of a botanic garden, a university professor said that “we should only eat the parts of a plant that the plant wants us to eat”. He was referring to the fruit, which many plants encourage animals to eat in order to spread their seeds in the environment (though not all fruits are edible). I don’t think he meant us to take his advice literally, but it is sensible to eat plants with caution. Alongside famous poisons including belladonna and hemlock, plants produce a variety of other molecules that aim to deter animals from eating them. Some of these molecules – such as ricin, which is produced by the castor oil plant – are so poisonous that tiny quantities can kill you. Others, like caffeine or the anti-malaria drug quinine, have less dramatic effects on the human body that we may find desirable or useful.

I recently visited The Alnwick Garden in north-east England, which has a special garden dedicated to educating visitors about the potential dangers of plants. In fact, some of the plants on display in the Poison Garden are so dangerous that visitors can only enter as part of a guided tour. I really enjoyed the tour and if you are ever in the area I recommend you pay the garden a visit.

The tour included some well-known poisonous plants, but the main message I took home from the tour was that many common garden plants are also potentially dangerous if they touch your skin or you accidently eat them. Below are a few examples of common plants that aren’t as benign as they might first seem:

Rhubarb (Rheum x hybridium)

While the pink fleshy stalks of the rhubarb plant are safe to eat and are commonly used in desserts, the leaves are highly toxic (1). This is thought to be due to the presence of high levels of oxalic acid, which can interfere with chemical reactions in the body by combining with calcium and other metals.

Common ivy (Hedera helix)

This rapidly growing vine is a haven for wildlife and attracts at least 70 species of nectar-feeding insects in its native range of Europe and Western Asia (2). Contact with ivy can cause an allergic skin reaction in some people, due to a natural pesticide in the leaves called falcarinol (3). Regardless of whether you are allergic to ivy or not, you should avoid eating this plant because its leaves contain saponins, which can cause vomiting, convulsions and even death.

Common nettle (Urtica dioica)

Children quickly learn that contact with common nettles results in a painful stinging sensation and skin inflammation. This is due to a cocktail of molecules including histamine, serotonin and oxalic acid, which is released from hairs on the surface of the leaves. For more information check out this cool infographic by Compound Interest.

Common laburnum (Laburnum anagyroides)

All parts of this small tree are poisonous, due to the presence of a molecule called cytisine, which has a similar structure to nicotine and has similar effects on the body. Laburnam is a member of the pea family and cases of laburnam poisoning are often caused by individuals mistaking laburnum seeds for peas and eating them (4). Mild cases may cause nausea and vomiting, but laburnum poisoning can also lead to insomnia, convulsions and coma.

These are just a few examples of common garden plants that can be harmful to humans and other animals. Fortunately, you can protect yourself against these and other poisonous plants by taking simple precautions, such as wearing gloves while gardening and carefully identifying edible plants when foraging.

Author’s note: Sorry for the long silence on this blog. My life has been quite chaotic in the last few months due to several events (expected/not expected, good/bad) and so the blog has had to take a back seat. Things are calming down a bit now so I’m hoping to get back into posting regularly, probably about twice a month. As ever, I’m always keen to receive guest posts so if you are interested in writing for Plant Scientist, please do get in touch.

In Lab Girl, scientist Hope Jahren has cleverly weaves a memoir of her own life with passages about the lives of plants, her scientific passion. From her childhood in a small town in Minnesota to her current position as a Professor at the University of Hawai’i, she gives a candid account that includes some of the adventures, funny incidents, obstacles, and shifts in her scientific thinking that happened along the way. The book is a fascinating window into the life of a gifted, passionate, yet (reassuringly) human scientist. If you haven’t read it yet, then I highly recommend you get your hands on a copy.

If you aren’t convinced by my mini-review, then I suggest you check out this longer review from the NY times.

A week early, the red poppy is the Organism of the Month of July here at Plant Scientist. I didn’t want to delay the publication of this post since there are loads of red poppies in flower in Europe at the moment!

At this time of year poppies seem to spring out of anywhere and everywhere they can. In the last few weeks I have seen them in gardens, motorway central reservations and even poking out of Norwich’s medieval city wall.

Humans have used poppies in food, medicines and beauty treatments for around 6,000 years. The opium poppy (Papaversomniforum) was widely used by the Greeks, Romans and even thought to be used by Neolithic tribes. When looking upon the pretty flower of the opium poppy, you could be forgiven for thinking that it is harmless. In fact, the opium poppy has been both a blessing and curse for humanity.

During the ripening of the opium poppy seed capsule, the head produces a milky sap, which is the source of the drug opium. In the 18th Century, China suffered greatly due to the addictive properties of opium. Britain, in an attempt to gain trade from China, supplied the Chinese with opium (from Bengal), despite resistance from the Chinese government. The effects of opium began to destabilise China and enabled the British to prosper in Opium Wars of the mid-19th Century. It was at this time (~1842) that Hong Kong became a colony of the British Empire and it was not returned to China until 1997. Continue reading →

One of the advantages of living in a small, green city with easy access to the countryside is that there are quite a few opportunities to forage wild things to eat. As a relative newcomer to a small city (I grew up in London) I’m only just starting to explore these opportunities. This week I used some flowers from some local elder trees to make elderflower cordial. It is only fitting that I feature the elder (Sambucus nigra) as the Organism of the Month.

The S. nigra is a deciduous shrub or small tree native to Europe and Asia (1). There are several other very closely-related species native to Asia and North America, such as the Mexican elderberry Sambucus mexicana. S. nigra is common in the UK and is found in woodland and hedgerows. Elder wood is soft, so not well-suited for construction, but is used to make traditional European flute instruments. Continue reading →

Plants, unlike animals, are sessile. This means that they are unable to move from where they grow. If you are a plant that has germinated into a nice nutrient rich soil with plenty of food and water this is not such a bad thing. However, if you find yourself in a spot which has a low nutrient content or is too dry, then you might find the inability to move yourself to a new patch a bit of a problem. One way to get yourself out of a sticky situation is to call on a friend who might be able to lend a hand. Plants call on their friends the arbuscular mycorrhizal fungi (AMF).

AMF are a group of fungi which form a close relationship with plants for mutual benefit. They are able to get nutrients such as phosphorus and nitrogen out of the soil and exchange them for sugars that the plant makes by photosynthesis. AMF get their name from the specialised structures they form within plant roots called arbuscules. Arbuscle translates from Ancient Greek as “little tree” which is exactly what these structures look like. They are highly branched fungal hyphae. The branches increase the surface area between the fungus and the plant that in turn increases the amount of nutrient-sugar exchange that can occur. The second half of their name, mycorrhiza, translates as “mushroom roots”. The fungal hyphae that grow out into the soil act like an extension of the plant roots. Continue reading →

Some people think that because I am a plant scientist I should also know a lot about gardening. Think again. The extent of my gardening is tending to some house-plants and a few herbs outside. All of these plants are pretty low maintenance (except the parsley, which needs more regular watering). This suits me because I love having plants around, but I tend to be a bit absent-minded about watering them, so I need plants that can tolerate dry conditions, like Aloe vera or thyme.

So why am I NOT an expert gardener? In short, because I’ve not had the years of training and experience that expert gardeners have. My research in plant science uses mostly molecular and cell biology techniques. I didn’t step foot in the greenhouses at my place of work for the whole of the first year of my PhD because I never needed to grow plants in soil. Instead, I was growing plants in sterile conditions (i.e. without microbes like bacteria and fungi) on a jelly-like substance called agar. Continue reading →